Dual buoy marker system



1968 G. E. MOTT 3,408,669

DUAL BUOY MARKER SYSTEM Filed June 20, 1967 United States Patent Oifice 3,408,669 Patented Nov. 5, 1968 ABSTRACT OF THE DISCLOSURE A system of dual buoys for marking the location of underwater well heads wherein an intermediate buoy is attached to a line connecting a surface buoy to the well head to maintain the lower portion of the connecting line under constant tension to prevent fouling.

Cross-reference to related applications This is a continuation-impart of application Ser. No. 474,091, filed July 22, 1965.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a buoy marker system for indicating the location of an object submerged in deep water.

Description of the prior art The ability to maintain a marker buoy indicating the location of an underwater object has become particularly important with the drilling of more and more underwater oil and gas wells especially in deep water locations. There is considerable expense in relocating an underwater well in deep water when a marker buoy indicating the location has been lost. The loss is usually caused by severe storm conditions which are fairly frequent in off-shore locations where most underwater wells have been drilled. The expense involved will better be appreciated when it is realized that the relocation and remarking of the well entails the services of surveyors, marine equipment and deep water divers.

The known buoy type marker systems consist of a surface buoy directly connected to the underwater well with a chain or steel cable. The losses encountered with a directly connected buoy have been numerous since the slack in the cable caused by surface variations such as waves, tide changes, etc. allows entanglement of the cable with the underwater well head apparatus which not only endangers the well but effectively shortens the cable thereby increasing the impact on the cable which increases the possibility of breakage thereof. One solution to the problem has been to enclose the underwater well head structure with a cage thereby eliminating the possibility of entangling the buoy cable with the underwater well head structure. Howe er, this is costly and introduces other problems.

SUMMARY OF THE INVENTION In accordance with the present invention a dual buoy marker system is provided for indicating the location of an object or obstruction submerged in deep water which comprises a surface buoy floating on the water surface and sufficiently emerged so as to be highly visible. The surface buoy is connected to the submerged object by a continuous connecting means which has an auxiliary buoyancy means attached thereto at a predetermined depth intermediate the surface buoy and the underwater object. The auxiliary buoyancy means has a net positive buoyancy so as to keep tension under all conditions in the portion of the connecting means between the auxiliary buoyancy means and the underwater object.

BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other features of this invention and the manner of obtaining them will become more apparent and the invention itself will be best understood, by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic diagram of the buoy marker system indicating the location of an underwater well.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, there is shown schematically a buoy marker system indicating the location of a deep water well head 16. Deep water usually refers to a depth of feet or more. The surface indication of the well head location is provided by buoy 10 which is connected to well head 16 by continuous line or cable 18. Buoy 10 is an elongated cylindrical shaped buoy generally known in the prior art as a spar buoy and as can be seen on the drawing, when it is floating a considerable extent of buoy 10 extends above the water surface 12 such that the buoy is easily visible from a considerable distance. To enhance the visibility of the buoy 10 it usually is made with alternate rings 13 of different colors, for example, alternately orange and white. Of course, buoys of different shapes can be utilized in the marker system of this invention, the only requirement being reliable buoyance and high visibility. I

An auxiliary buoy 14 is provided which is connected by means of a clamp or similar suitable connecting device 19 to continuous cable 18 at an intermediate point on cable 18. Auxiliary buoy 14 is designed to have a net positive buoyancy, that is a vertical upward buoyant force,

. such that the portion of connecting line or cable 18 between auxiliary buoy 14 the well head equipment 16 will be under constant tension. Auxiliary buoy 14 is preferably connected to cable 18 at a depth of 50 or 60 feet below the surface of the water. This depth is known to be below the most severe surface wave action and thus the auxiliary buoy 14 will be substantially unaffected by storm, high wave and wind conditions on the surface. Since the lower portion of cable 18 between auxiliary buoy 14 and underwater well head equipment 16 is maintained under constant tension by the buoy 14, and since buoy 14 is below the surface wave action level, the lower portion of cable 18 will under no conditions be slack and, therefore, the danger of entanglement with the underwater well head equipment is eliminated. The actual connection of the cable 18 to the surface buoy 10, the underwater well head equipment 16 and the spherical auxiliary buoy 14 is made by means of swivel jaw and eye connectors 21, 22 and 23, respectively, which are well known in the art. The use of swivel type connectors eliminates twisting of the cable and thus reduces failure of the system because of cable breakage.

Auxiliary buoy 14 has extending therefrom at opposite ends of a diameter therethrough an eye 20, one of which is connected to swivel jaw and eye 23, which in turn is connected by means of a short length of cable 28 to clamp 30 and clamp 30 is fastened at a predetermined intermediate point to continuous cable 10. The cable may be attached to the swivel jaw and eye in each instance by overlapping the portion of the cable passed through the swivel eye section. This overlapping portion is surrounded by a thimble 24 which is held in place by clamp 26.

The upper portion of continuous line or cable .18 is connected to auxiliary buoy 14. This portion of cable 18 is made sufliciently long such that when surface buoy 10 is floating at mean sea level 12 there is no tension on the line and surface buoy 10 can drift with respect to auxiliary buoy 14. When the upper portion of cable 18 reaches the limit of its length so that tension is applied thereto, auxiliary buoy 14 acts as a shock absorber in the line because of its being pulled horizontally through the water before continuous line or cable 18 is pulled into a taut straight line between surface buoy 10 and well equipment 16. The uppenmost end of line 18 is connected to an eye extending from the bottom of surface buoy 10. The connection is made by a swivel jaw and eye arrangement 21 similar to the connections made to auxiliary buoy 14 and well equipment 16. These swivel type connections again, are to prevent twisting of the connecting line. In the event, surface buoy 10 should be lost the auxiliary buoy 14 is not etfected and can still be much more easily located than the deep water well head equipment 16. To aid in the locating of the auxiliary buoy 14, it is usually colored, for example, white. This can be accomplished by coating the sphere with a gel-coating of appropriate color.

On the other hand, if for any reason auxiliary buoy 14 is damaged or loses its buoyancy it can readily be replaced by another buoy without in any way disconnecting line 18 from surface buoy 10 to well head 16. In the systems of the prior art, separate lines are employed for connecting the auxiliary buoy to the well head and for connecting the surface buoy to the auxiliary buoy. In such a system should the auxiliary buoy become damaged or its buoyancy impaired, it is necessary to disconnect both lines at the auxiliary buoy in order to effect a replacement thereof. With such separate line system it is easily possible for an accident to occur while the lines are disconnected with the loss of contact with the upper end of the line connected to the well head. In such event, contact with the wellhead is lost completely and serious ditficulties may be incurred as a result. With the system of the present invention, the auxiliary or intermediate buoy may be dis connected from the moving line and replaced without any danger of loss of contact with the well head.

Obviously, many modifications and variations of the invention as hereinabove set forth, may be, made without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the appended claim.

I claim:

1. A buoy marker system for indicating the location of the well head of an underwater well submerged in deep water, comprising a surface buoy floating on the water surface, continuous connecting means attaching said surface buoy to said well head, a tethered auxiliary buoyancy means having a fixed buoyancy and a swivel connector attached by a line and clamping device to said connecting means at a predetermined depth intermediate said surface buoy and said well head, said auxiliary buoyancy means having a net positive buoyancy to keep tension in the connecting means between the auxiliary buoyancy means and the well head.

References Cited UNITED STATES PATENTS 612,109 10/ 1898 H-utchins 9-8 3,204,708 9/1965 Berne 98 X 3,295,489 1/ 1967 Bossa 9-8 X MILTON BUCHLER, Primary Examiner.

T. MAJOR, Assistant Examiner. 

